Special equipment: a deep-frying thermometer and a 1-inch ice cream scoop
For the crab hush puppies: In a medium bowl, whisk the cornmeal, flour, baking powder, kosher salt, sugar and garlic powder. In a separate small bowl, whisk the buttermilk and egg. Make a well in the dry ingredients and begin to gently stir in the buttermilk mixture (I use a wooden spoon). Do not overmix. Gently stir in the crab and scallions until just mixed.
For the cilantro-jalapeno dip: Combine the cilantro, mayonnaise, garlic powder, sea salt, pepper, reserved scallion greens and jalapeno in a blender and blend until pureed. Refrigerate until serving time. This can be made a day in advance.
Heat several inches of canola oil in a Dutch oven to 350 degrees F. (There should be enough oil for the hush puppies to be completely submerged.) Use a 1-inch ice cream scoop to drop the batter into the hot oil in batches. Fry until deep golden brown, about 4 minutes. While the hush puppies are hot, sprinkle with a pinch of sea salt. Serve immediately with the dip.